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| 5. |
- Dzhambov, A. M., et al.
(författare)
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Protective effect of restorative possibilities on cognitive function and mental health in children and adolescents: A scoping review including the role of physical activity
- 2023
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Ingår i: Environmental Research. - 0013-9351 .- 1096-0953. ; 233
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Forskningsöversikt (refereegranskat)abstract
- Background The exposome approach can be a powerful tool for understanding the intertwining of social, physical, and internal influences that shape mental health and cognitive development throughout childhood. To distil conceptual models for subsequent analyses, the EU-funded project Early Environmental quality and Life-course mental health effects (Equal-Life) has conducted literature reviews on potential mediators linking the expo some to these outcomes. We report on a scoping review and a conceptual model of the role of restorative possibilities and physical activity. Methods Peer-reviewed studies published since the year 2000 in English, on the association between the exposome and mental health/cognition in children/adolescents, and quantitatively investigating restoration/restorative quality as a mediating variable were considered. Database searches were last updated in December 2022. We used an unstructured expert-driven approach to fill in gaps in the reviewed literature.Results Five records of three distinct studies were identified, indicating a scarcity of empirical evidence in this newly developing research area. Not only were these studies few in numbers, but also cross-sectional, lending only tentative support to the idea that perceived restorative quality of adolescent's living environment might mediate the association between greenspace and mental health. Physical activity emerged as a mediator leading to better psychological outcomes in restorative environments. We provide a critical discussion of potential caveats when investigating the restoration mechanism in children and propose a hierarchical model including restoration, physical activity, and relational dynamics between children and their environment, including social context, as well as restorative environments other than nature.Conclusions It is justified to further explore the role of restoration and physical activity as mediators in the association between early-life exposome and mental health/cognitive development. It is important to consider the child perspective and specific methodological caveats. Given the evolving conceptual definitions/operationalizations, Equal-Life will attempt to fill in a critical gap in the literature.
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| 8. |
- Barnes, D, et al.
(författare)
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SAFETY AND TOLERABILITY OF TERIFLUNOMIDE IN CLINICAL STUDIES
- 2015
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Ingår i: JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY. - : BMJ. - 0022-3050 .- 1468-330X. ; 86:11
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Teriflunomide, approved for the treatment of relapsing-remitting multiple sclerosis, has a well-characterized safety profile based on individual clinical studies. We report pooled safety and tolerability data from four, double-blind, placebo-controlled trials of teriflunomide. Post-approval updates on hair thinning and pregnancy outcomes, sometimes concerns for patients initiating teriflunomide, are reported.MethodsData were pooled from phase 2 (NCT01487096) and phase 3 TEMSO (NCT00134563), TOWER (NCT00751881), and TOPIC (NCT00622700) studies. Patients were randomized to receive teriflunomide 14 mg, 7 mg, or placebo. Safety analyses were performed for all patients exposed to teriflunomide.ResultsThe pooled dataset included 3044 patients. Commonly reported adverse events (AEs) were in accordance with individual clinical studies, most being transient and mild-to-moderate in intensity. Incidence of hepatic AEs was higher in teriflunomide groups; however, serious hepatic AEs were similar across groups (∼2–3%). Hair thinning was higher in teriflunomide than placebo groups, but typically resolved on treatment without intervention and led to discontinuation in <2% of patients. No structural or functional abnormalities were reported in 42 newborns from teriflunomide-exposed parents.ConclusionsThese data from >6800 patient-years of teriflunomide exposure were consistent with individual studies and no new, unexpected safety signals were observed. (Study supported by Genzyme, a Sanofi company).
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| 9. |
- Grinberg, Marianna, et al.
(författare)
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Toxicogenomics directory of chemically exposed human hepatocytes
- 2014
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 1432-0738 .- 0340-5761. ; 88:12, s. 2261-2287
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Tidskriftsartikel (refereegranskat)abstract
- A long-term goal of numerous research projects is to identify biomarkers for in vitro systems predicting toxicity in vivo. Often, transcriptomics data are used to identify candidates for further evaluation. However, a systematic directory summarizing key features of chemically influenced genes in human hepatocytes is not yet available. To bridge this gap, we used the Open TG-GATES database with Affymetrix files of cultivated human hepatocytes incubated with chemicals, further sets of gene array data with hepatocytes from human donors generated in this study, and publicly available genome-wide datasets of human liver tissue from patients with non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular cancer (HCC). After a curation procedure, expression data of 143 chemicals were included into a comprehensive biostatistical analysis. The results are summarized in the publicly available toxicotranscriptomics directory (http://wiki.toxbank.net/toxicogenomics-map/) which provides information for all genes whether they are up- or downregulated by chemicals and, if yes, by which compounds. The directory also informs about the following key features of chemically influenced genes: (1) Stereotypical stress response. When chemicals induce strong expression alterations, this usually includes a complex but highly reproducible pattern named 'stereotypical response.' On the other hand, more specific expression responses exist that are induced only by individual compounds or small numbers of compounds. The directory differentiates if the gene is part of the stereotypical stress response or if it represents a more specific reaction. (2) Liver disease-associated genes. Approximately 20 % of the genes influenced by chemicals are up- or downregulated, also in liver disease. Liver disease genes deregulated in cirrhosis, HCC, and NASH that overlap with genes of the aforementioned stereotypical chemical stress response include CYP3A7, normally expressed in fetal liver; the phase II metabolizing enzyme SULT1C2; ALDH8A1, known to generate the ligand of RXR, one of the master regulators of gene expression in the liver; and several genes involved in normal liver functions: CPS1, PCK1, SLC2A2, CYP8B1, CYP4A11, ABCA8, and ADH4. (3) Unstable baseline genes. The process of isolating and the cultivation of hepatocytes was sufficient to induce some stress leading to alterations in the expression of genes, the so-called unstable baseline genes. (4) Biological function. Although more than 2,000 genes are transcriptionally influenced by chemicals, they can be assigned to a relatively small group of biological functions, including energy and lipid metabolism, inflammation and immune response, protein modification, endogenous and xenobiotic metabolism, cytoskeletal organization, stress response, and DNA repair. In conclusion, the introduced toxicotranscriptomics directory offers a basis for a rationale choice of candidate genes for biomarker evaluation studies and represents an easy to use source of background information on chemically influenced genes.
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| 10. |
- Krebs, Alice, et al.
(författare)
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The EU-ToxRisk method documentation, data processing and chemical testing pipeline for the regulatory use of new approach methods
- 2020
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 94:7, s. 2435-2461
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Tidskriftsartikel (refereegranskat)abstract
- Hazard assessment, based on new approach methods (NAM), requires the use of batteries of assays, where individual tests may be contributed by different laboratories. A unified strategy for such collaborative testing is presented. It details all procedures required to allow test information to be usable for integrated hazard assessment, strategic project decisions and/or for regulatory purposes. The EU-ToxRisk project developed a strategy to provide regulatorily valid data, and exemplified this using a panel of > 20 assays (with > 50 individual endpoints), each exposed to 19 well-known test compounds (e.g. rotenone, colchicine, mercury, paracetamol, rifampicine, paraquat, taxol). Examples of strategy implementation are provided for all aspects required to ensure data validity: (i) documentation of test methods in a publicly accessible database; (ii) deposition of standard operating procedures (SOP) at the European Union DB-ALM repository; (iii) test readiness scoring accoding to defined criteria; (iv) disclosure of the pipeline for data processing; (v) link of uncertainty measures and metadata to the data; (vi) definition of test chemicals, their handling and their behavior in test media; (vii) specification of the test purpose and overall evaluation plans. Moreover, data generation was exemplified by providing results from 25 reporter assays. A complete evaluation of the entire test battery will be described elsewhere. A major learning from the retrospective analysis of this large testing project was the need for thorough definitions of the above strategy aspects, ideally in form of a study pre-registration, to allow adequate interpretation of the data and to ensure overall scientific/toxicological validity.
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| 12. |
- Persson Waye, Kerstin, 1959, et al.
(författare)
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Adopting a child perspective for exposome research on mental health and cognitive development - Conceptualisation and opportunities.
- 2023
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Ingår i: Environmental research. - 0013-9351 .- 1096-0953. ; 239:Pt 1
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Tidskriftsartikel (refereegranskat)abstract
- Mental disorders among children and adolescents pose a significant global challenge. The exposome framework covering the totality of internal, social and physical exposures over a lifetime provides opportunities to better understand the causes of and processes related to mental health, and cognitive functioning. The paper presents a conceptual framework on exposome, mental health, and cognitive development in children and adolescents, with potential mediating pathways, providing a possibility for interventions along the life course. The paper underscores the significance of adopting a child perspective to the exposome, acknowledging children's specific vulnerability, including differential exposures, susceptibility of effects and capacity to respond; their susceptibility during development and growth, highlighting neurodevelopmental processes from conception to young adulthood that are highly sensitive to external exposures. Further, critical periods when exposures may have significant effects on a child's development and future health are addressed. The paper stresses that children's behaviour, physiology, activity pattern and place for activities make them differently vulnerable to environmental pollutants, and calls for child-specific assessment methods, currently lacking within today's health frameworks. The importance of understanding the interplay between structure and agency is emphasized, where agency is guided by social structures and practices and vice-versa. An intersectional approach that acknowledges the interplay of social and physical exposures as well as a global and rural perspective on exposome is further pointed out. To advance the exposome field, interdisciplinary efforts that involve multiple scientific disciplines are crucial. By adopting a child perspective and incorporating an exposome approach, we can gain a comprehensive understanding of how exposures impact children's mental health and cognitive development leading to better outcomes.
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| 13. |
- Blomgren, Klas, 1963, et al.
(författare)
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Pathological apoptosis in the developing brain
- 2007
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Ingår i: Apoptosis. - : Springer Science and Business Media LLC. - 1360-8185 .- 1573-675X. ; 12:5, s. 993-1010
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Forskningsöversikt (refereegranskat)abstract
- More than half of the initially-formed neurons are deleted in certain brain regions during normal development. This process, whereby cells are discretely removed without interfering with the further development of remaining cells, is called programmed cell death (PCD). The term apoptosis is used to describe certain morphological manifestations of PCD. Many of the effectors of this developmental cell death program are highly expressed in the developing brain, making it more susceptible to accidental activation of the death machinery, e.g. following hypoxia-ischemia or irradiation. Recent evidence suggests, however, that activation and regulation of cell death mechanisms under pathological conditions do not exactly mirror physiological, developmentally regulated PCD. It may be argued that the conditions after e.g. ischemia are not even compatible with the execution of PCD as we know it. Under pathological conditions cells are exposed to various stressors, including energy failure, oxidative stress and unbalanced ion fluxes. This results in parallel triggering and potential overshooting of several different cell death pathways, which then interact with one another and result in complex patterns of biochemical manifestations and cellular morphological features. These types of cell death are here called "pathological apoptosis," where classical hallmarks of PCD, like pyknosis, nuclear condensation and caspase-3 activation, are combined with non-PCD features of cell death. Here we review our current knowledge of the mechanisms involved, with special focus on the potential for therapeutic intervention tailored to the needs of the developing brain.
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| 16. |
- Davis, TH, et al.
(författare)
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Problem-based learning of research skills
- 2006
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Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 39:1, s. 120-128
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To determine whether a short-term, problem-based educational intervention leads to increased research activity among health care practitioners. Subjects and Methods: Participant's success was evaluated as a composite of 2 outcomes. These were (1) reporting results for the project designed during the practicum and (2) conducting subsequent research activities. The study population included 36 clinical research outcomes projects developed by clinical practitioners, postgraduate trainees, and medical students during 6 separate practicums. All project teams received the same educational intervention, an "outcomes research practicum" that was divided into 4 primary learning modules administered over a I to 4 month period. Each module included a preparatory videotape lecture, supplemental readings, and a 90-minute interactive laboratory session during which faculty members worked with participants to develop answers to a series of predefined questions relating to the design of clinical outcomes research projects. Follow-up continued for a minimum of 12 months and a maximum of 36 months. Results: Eighty-three percent of project teams completed all 4 practicum modules, and 69% completed one of the study outcomes (50% completed their research project and 47% completing a subsequent research activity). Practitioners were more likely to complete subsequent research activities, whereas trainees were more likely to complete their study project. Discussion: This short-term, problem-based educational intervention was successful in increasing the collective research activities of participants. Further, more rigorous structured research is needed to determine the ultimate impact on practice change and patient outcomes. (c) 2006 Elsevier Inc. All rights reserved.
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| 17. |
- Delp, Johannes, et al.
(författare)
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Neurotoxicity and underlying cellular changes of 21 mitochondrial respiratory chain inhibitors
- 2021
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Ingår i: Archives of Toxicology. - : Springer. - 0340-5761 .- 1432-0738. ; 95:2, s. 591-615
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Tidskriftsartikel (refereegranskat)abstract
- Inhibition of complex I of the mitochondrial respiratory chain (cI) by rotenone and methyl-phenylpyridinium (MPP +) leads to the degeneration of dopaminergic neurons in man and rodents. To formally describe this mechanism of toxicity, an adverse outcome pathway (AOP:3) has been developed that implies that any inhibitor of cI, or possibly of other parts of the respiratory chain, would have the potential to trigger parkinsonian motor deficits. We used here 21 pesticides, all of which are described in the literature as mitochondrial inhibitors, to study the general applicability of AOP:3 or of in vitro assays that are assessing its activation. Five cI, three complex II (cII), and five complex III (cIII) inhibitors were characterized in detail in human dopaminergic neuronal cell cultures. The NeuriTox assay, examining neurite damage in LUHMES cells, was used as in vitro proxy of the adverse outcome (AO), i.e., of dopaminergic neurodegeneration. This test provided data on whether test compounds were unspecific cytotoxicants or specifically neurotoxic, and it yielded potency data with respect to neurite degeneration. The pesticide panel was also examined in assays for the sequential key events (KE) leading to the AO, i.e., mitochondrial respiratory chain inhibition, mitochondrial dysfunction, and disturbed proteostasis. Data from KE assays were compared to the NeuriTox data (AO). The cII-inhibitory pesticides tested here did not appear to trigger the AOP:3 at all. Some of the cI/cIII inhibitors showed a consistent AOP activation response in all assays, while others did not. In general, there was a clear hierarchy of assay sensitivity: changes of gene expression (biomarker of neuronal stress) correlated well with NeuriTox data; mitochondrial failure (measured both by a mitochondrial membrane potential-sensitive dye and a respirometric assay) was about 10-260 times more sensitive than neurite damage (AO); cI/cIII activity was sometimes affected at > 1000 times lower concentrations than the neurites. These data suggest that the use of AOP:3 for hazard assessment has a number of caveats: (i) specific parkinsonian neurodegeneration cannot be easily predicted from assays of mitochondrial dysfunction; (ii) deriving a point-of-departure for risk assessment from early KE assays may overestimate toxicant potency.
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| 18. |
- Fukuda, Hirotsugu, et al.
(författare)
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Irradiation-induced progenitor cell death in the developing brain is resistant to erythropoietin treatment and caspase inhibition
- 2004
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Ingår i: Cell Death Differ. - Univ Gothenburg, Dept Physiol, Perinatal Ctr, SE-40530 Gothenburg, Sweden. Osaka Univ, Sch Med, Dept Obstet & Gynecol, Suita, Osaka 5650871, Japan. Zhengzhou Univ, Affiliated Hosp 3, Dept Pediat, Zhengzhou 450052, Peoples R China. Uppsala Univ, Dept Neurosci, SE-75123 Uppsala, Sweden. Sahlgrens Univ Hosp, Dept Radiat Phys, SE-41345 Gothenburg, Sweden. H Lundbeck & Co AS, Mol Dis Biol, DK-2500 Copenhagen, Denmark. Sahlgrens Univ Hosp, Dept Oncol, SE-41345 Gothenburg, Sweden. Queen Silvia Childrens Hosp, Dept Pediat, SE-41685 Gothenburg, Sweden. : NATURE PUBLISHING GROUP. - 1350-9047 .- 1476-5403. ; 11:11, s. 1166-78
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Tidskriftsartikel (refereegranskat)abstract
- One hemisphere of postnatal day 8 (P8) rats or P10 mice was irradiated with a single dose of 4-12 Gy, and animals were killed from 2 h to 8 weeks after irradiation (IR). In the subventricular zone (SVZ) and the granular cell layer (GCL) of the dentate gyrus, harboring neural and other progenitor cells, nitrosylation and p53 peaked 2-12 h after IR, followed by markers for active caspase-3, apoptosis-inducing factor and TUNEL (6-24 h). Ki67-positive (proliferating) cells had disappeared by 12 h and partly reappeared by 7 days post-IR. The SVZ and GCL areas decreased approximately 50% 7 days after IR. The development of white matter was hampered, resulting in 50-70% less myelin basic protein staining. Pretreatment with erythropoietin did not confer protection against IR. Caspase inhibition by overexpression of XIAP prevented caspase-9 and caspase-3 activation but not cell death, presumably because of increased caspase-independent cell death.
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| 19. |
- Gil, Joana, et al.
(författare)
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Asialoerythropoetin is not effective in the R6/2 line of Huntington's disease mice
- 2004
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Ingår i: BMC Neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an expanded CAG repeat in the HD gene. Both excitotoxicity and oxidative stress have been proposed to play important roles in the pathogenesis of HD. Since no effective treatment is available, this study was designed to explore the therapeutic potential of erythropoietin (EPO), a cytokine that has been found to prevent excitotoxicity, and to promote neurogenesis. To avoid the side effects of a raised hematocrit, we used asialoerythropoietin (asialoEPO), a neuroprotective variant of EPO that lacks erythropoietic effects in mice. R6/2 transgenic HD mice were treated with this cytokine from five to twelve weeks of age. Results: We provide new evidence that cell proliferation in the dentate gyrus of the R6/2 hippocampus is reduced by 50% compared to wild-type littermate controls. However, we found that the asialoEPO treatment did not affect the progression of motor symptoms, weight loss or the neuropathological changes. Furthermore, cell proliferation was not enhanced. Conclusions: We conclude that the chosen protocol of asialoEPO treatment is ineffective in the R6/2 model of HD. We suggest that reduced hippocampal cell proliferation may be an important and novel neuropathological feature in R6 HD mice that could be assessed when evaluating potential therapies.
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| 20. |
- Hansson, Oskar, et al.
(författare)
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Additive effects of caspase inhibitor and lazaroid on the survival of transplanted rat and human embryonic dopamine neurons
- 2000
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 164:1, s. 102-111
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Tidskriftsartikel (refereegranskat)abstract
- Major practical constraints on neural grafting in Parkinson's disease are the shortage of human donor tissue and the great loss of dopamine neurons during the grafting procedure. The vast majority of implanted embryonic dopamine neurons are believed to die within a few days of transplantation surgery, at least in part through apoptosis. We have previously found that survival of nigral grafts in rodents can be significantly augmented by pretreatment with the caspase inhibitor Ac-YVAD-cmk or by lazaroids (lipid peroxidation inhibitors). We now report that pretreatment with the caspase inhibitor Ac-DEVD-cmk, but not z-VAD-fmk, results in a significantly improved survival of transplanted dopamine neurons of similar magnitude to that achieved in this study using Ac-YVAD-cmk (both 220-230% of control). In addition, we found that treatment of the graft tissue with tirilazad mesylate (a lazaroid allowed for clinical use) almost doubled the survival of grafted dopamine neurons. When Ac-YVAD-cmk and tirilazad mesylate treatments were combined, the number of surviving dopamine neurons increased significantly further to 280% of control. Importantly, the same combination of neuroprotectants enhanced the survival of human dopamine neurons xenotransplanted to immunosuppressed rats (to 240% of control). In conclusion, these results suggest that combining treatments that counteract oxidative stress and caspase activation is a valuable strategy to enhance nigral graft survival that should be considered for clinical application.
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| 21. |
- Hansson, Oskar, et al.
(författare)
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Transgenic mice expressing a Huntington's disease mutation are resistant to quinolinic acid-induced striatal excitotoxicity
- 1999
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Ingår i: Proceedings of the National Academy of Sciences. - 1091-6490. ; 96:15, s. 8727-8732
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease (HD) is a hereditary neurodegenerative disorder presenting with chorea, dementia, and extensive striatal neuronal death. The mechanism through which the widely expressed mutant HD gene mediates a slowly progressing striatal neurotoxicity is unknown. Glutamate receptor-mediated excitotoxicity has been hypothesized to contribute to the pathogenesis of HD. Here we show that transgenic HD mice expressing exon 1 of a human HD gene with an expanded number of CAG repeats (line R6/1) are strongly protected from acute striatal excitotoxic lesions. Intrastriatal infusions of the N-methyl-D-aspartate (NMDA) receptor agonist quinolinic acid caused massive striatal neuronal death in wild-type mice, but no damage in transgenic HD littermates. The remarkable neuroprotection in transgenic HD mice occurred at a stage when they had not developed any neurological symptoms caused by the mutant HD gene. At this stage there was no change in the number of striatal neurons and astrocytes in untreated R6/1 mice, although the striatal volume was decreased by 17%. Moreover, transgenic HD mice had normal striatal levels of NMDA receptors, calbindin D28k (calcium buffer), superoxide dismutase activity (antioxidant enzyme), Bcl-2 (anti-apoptotic protein), heat shock protein 70 (stress-induced anti-apoptotic protein), and citrate synthase activity (mitochondrial enzyme). We propose that the presence of exon 1 of the mutant HD gene induces profound changes in striatal neurons that render these cells resistant to excessive NMDA receptor activation.
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| 23. |
- Krebs, Alice, et al.
(författare)
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Template for the Description of Cell-Based Toxicological Test Methods to Allow Evaluation and Regulatory Use of the Data
- 2019
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Ingår i: Altex. - : ALTEX Edition. - 1868-596X .- 1868-8551. ; 36:4, s. 682-699
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Only few cell-based test methods are described by Organisation for Economic Co-operation and Development (OECD) test guidelines or other regulatory references (e.g., the European Pharmacopoeia). The majority of toxicity tests still falls into the category of non-guideline methods. Data from these tests may nevertheless be used to support regulatory decisions or to guide strategies to assess compounds (e.g., drugs, agrochemicals) during research and development if they fulfill basic requirements concerning their relevance, reproducibility and predictivity. Only a method description of sufficient clarity and detail allows interpretation and use of the data. To guide regulators faced with increasing amounts of data from non-guideline studies, the OECD formulated Guidance Document 211 (GD211) on method documentation for the purpose of safety assessment. As GD211 is targeted mainly at regulators, it leaves scientists less familiar with regulation uncertain as to what level of detail is required and how individual questions should be answered. Moreover, little attention was given to the description of the test system (i.e., cell culture) and the steps leading to it being established in the guidance. To address these issues, an annotated toxicity test method template (ToxTemp) was developed (i) to fulfill all requirements of GD211, (ii) to guide the user concerning the types of answers and detail of information required, (iii) to include acceptance criteria for test elements, and (iv) to define the cells sufficiently and transparently. The fully annotated ToxTemp is provided here, together with reference to a database containing exemplary descriptions of more than 20 cell-based tests.
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| 26. |
- Lotharius, J, et al.
(författare)
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Progressive degeneration of human mesencephalic neuron-derived cells triggered by dopamine-dependent oxidative stress is dependent on the mixed-lineage kinase pathway
- 2005
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 25:27, s. 6329-6342
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Tidskriftsartikel (refereegranskat)abstract
- Models of Parkinson's disease (PD) based on selective neuronal death have been used to study pathogenic mechanisms underlying nigral cell death and in some instances to develop symptomatic therapies. For validation of putative neuroprotectants, a model is desirable in which the events leading to neurodegeneration replicate those occurring in the disease. We developed a human in vitro model of PD based on the assumption that dysregulated cytoplasmic dopamine levels trigger cell loss in this disorder. Differentiated human mesencephalic neuron-derived cells were exposed to methamphetamine (METH) to promote cytoplasmic dopamine accumulation. In the presence of elevated iron concentrations, as observed in PD, increased cytosolic dopamine led to oxidative stress, c-Jun N-terminal kinase (JNK) pathway activation, neurite degeneration, and eventually apoptosis. We examined the role of the mixed-lineage kinases (MLKs) in this complex degenerative cascade by using the potent inhibitor 3,9-bis[( ethylthio) methyl]-K-252a (CEP1347). Inhibition of MLKs not only prevented FeCl2+/METH- induced JNK activation and apoptosis but also early events such as neurite degeneration and oxidative stress. This broad neuroprotective action of CEP1347 was associated with increased expression of an oxidative stress-response modulator, activating transcription factor 4. As a functional consequence, transcription of the cystine/glutamate and glycine transporters, cellular cystine uptake and intracellular levels of the redox buffer glutathione were augmented. In conclusion, this new human model of parkinsonian neurodegeneration has the potential to yield new insights into neurorestorative therapeutics and suggests that enhancement of cytoprotective mechanisms, in addition to blockade of apoptosis, may be essential for disease modulation.
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| 27. |
- Osato, Kazuhiro, et al.
(författare)
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Carbamylated Erythropoietin Decreased Proliferation and Neurogenesis in the Subventricular Zone, but Not the Dentate Gyrus, After Irradiation to the Developing Rat Brain
- 2018
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Cranial radiotherapy for pediatric brain tumors causes progressive, debilitating late effects, including cognitive decline. Erythropoietin (EPO) has been shown to be neuroprotective and to promote neuroregeneration. Carbamylated erythropoietin (CEPO) retains the protective properties of EPO but is not erythrogenic. To study the effects of CEPO on the developing brain exposed to radiotherapy, a single irradiation (IR) dose of 6Gy was administered to the brains of postnatal day 9 (P9) rats, and CEPO (40 mu g/kg s.c.) was injected on P8, P9, P11, P13, and P15. To examine proliferation, 5-Bromo-2-deoxyuridine (BrdU) was injected on P15, P16, and P17. CEPO administration did not affect BrdU incorporation in the granule cell layer (GCL) of the hippocampus or in the subventricular zone (SVZ) as quantified 7 days after the last BrdU injection, whereas IR decreased BrdU incorporation in the GCL and SVZ by 63% and 18%, respectively. CEPO did not affect BrdU incorporation in the GCL of irradiated brains, although it was reduced even further (to 31%) in the SVZ. To evaluate the effect of CEPO on neurogenesis, BrdU/doublecortin double-positive cells were quantified. CEPO did not affect neurogenesis in non-irradiated brains, whereas IR decreased neurogenesis by 58% in the dentate gyrus (DG) but did not affect it in the SVZ. In the DG, CEPO did not affect the rate of neurogenesis following IR, whereas in the SVZ, the rate decreased by 30% following IR compared with the rate in vehicle-treated rats. Neither CEPO nor IR changed the number of microglia. In summary, CEPO did not promote neurogenesis in non-irradiated or irradiated rat brains and even aggravated the decreased neurogenesis in the SVZ. This raises concerns regarding the use of EPO-related compounds following radiotherapy.
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| 28. |
- Schierle, Gabriele, et al.
(författare)
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Caspase inhibition reduces apoptosis and increases survival of nigral transplants
- 1999
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 5:1, s. 97-100
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Tidskriftsartikel (refereegranskat)abstract
- Transplantation of embryonic nigral tissue ameliorates functional deficiencies in Parkinson disease. The main practical constraints of neural grafting are the shortage of human donor tissue and the poor survival of dopaminergic neurons grafted into patients, which is estimated at 5-10% (refs. 3,4). The required amount of human tissue could be considerably reduced if the neuronal survival was augmented. Studies in rats indicate that most implanted embryonic neurons die within 1 week of transplantation, and that most of this cell death is apoptotic. Modified peptides, such as acetyl-tyrosinyl-valyl-alanyl-aspartyl-chloro-methylketone (Ac-YVAD-cmk), that specifically inhibit proteases of the caspase family effectively block apoptosis in a plethora of experimental paradigms, such as growth factor withdrawal, excitotoxicity, axotomy, cerebral ischemia and brain trauma. Here we examined the effects of caspase inhibition by Ac-YVAD-cmk on cell death immediately after donor tissue preparation and on long-term graft survival. Treatment of the embryonic nigral cell suspension with Ac-YVAD-cmk mitigated DNA fragmentation and reduced apoptosis in transplants. It also increased survival of dopaminergic neurons grafted to hemiparkinsonian rats, and thereby substantially improved functional recovery.
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| 29. |
- Schierle, Gabriele, et al.
(författare)
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Neuronal death in nigral grafts in the absence of poly (ADP-ribose) polymerase activation
- 1999
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Ingår i: NeuroReport. - 1473-558X. ; 10:16, s. 3347-3351
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Tidskriftsartikel (refereegranskat)abstract
- The exact causes of the extensive cell death in nigral transplants are still unknown. Since poly-(ADP-ribose) polymerase (PARP) overactivation has been implicated in neuronal death, we examined the effects of PARP on the survival of nigral grafts by using donor tissue from PARP knock-out or wild-type mice. Eight hours after preparation of the nigral cell suspension, cell damage was quantified by measurement of lactate dehydrogenase release, DNA fragmentation and caspase activation. At this stage, PARP deletion had no protective effect. Moreover, neither the survival of transplanted dopaminergic neurons, nor the functional recovery of hemiparkinsonian graft recipients were improved by the absence of PARP. We conclude that cell death in embryonic nigral grafts is not affected by the absence of PARP activation.
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| 30. |
- Schierle, G S, et al.
(författare)
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Differential effects of Bcl-2 overexpression on fibre outgrowth and survival of embryonic dopaminergic neurons in intracerebral transplants
- 1999
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Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X. ; 11:9, s. 81-3073
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Tidskriftsartikel (refereegranskat)abstract
- The causes of death of transplanted neurons are not known in detail, but apoptotic mechanisms involving caspase activation are likely to play a role. We examined whether overexpression of the anti-apoptotic protein Bcl-2 may enhance the survival of dopaminergic [tyrosine hydroxylase (TH)-immunoreactive] grafted neurons. For this purpose, we prepared cells from embryonic day 13 ventral mesencephalon (VM) of mice overexpressing human Bcl-2, or from their wild-type littermates. The bcl-2 transgene was strongly expressed in these cells, and resulted in protection of neuronal cultures from death triggered by serum deprivation or exposure to staurosporine. To model pretransplantation stress more closely in vitro, we stored dissociated embryonic mesencephalic cells for 8 h in the same type of medium used for intracerebral transplantation. This resulted in massive cell death as quantified by lactate dehydrogenase (LDH) release, and increased DNA fragmentation. Although this cell loss was strongly reduced by a caspase inhibitor, Bcl-2 had no significant protective effect. Finally, mesencephalic cell suspensions were xenografted into the striatum of immunosuppressed hemiparkinsonian rats. Neither the survival of TH-immunopositive transplanted neurons nor the functional recovery of the rats was improved by Bcl-2, although the Bcl-2 protein was strongly expressed in transgenic grafts 5 weeks after implantation, and dopaminergic fibre outgrowth from the grafts was significantly improved. These data suggest that cell death in neuronal transplants involves apoptotic mechanisms that can bypass negative regulation by Bcl-2.
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| 31. |
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| 32. |
- Volbracht, C., et al.
(författare)
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Neuroprotective properties of memantine in different in vitro and in vivo models of excitotoxicity
- 2006
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Ingår i: Eur J Neurosci. - : Wiley. - 0953-816X. ; 23:10, s. 2611-22
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenesis of stroke, trauma and chronic degenerative diseases, such as Alzheimer's disease (AD), has been linked to excitotoxic processes due to inappropriate stimulation of the N-methyl-D-aspartate receptor (NMDA-R). Attempts to use potent competitive NMDA-R antagonists as neuroprotectants have shown serious side-effects in patients. As an alternative approach, we were interested in the anti-excitotoxic properties of memantine, a well-tolerated low affinity uncompetitive NMDA-R antagonist presently used as an anti-dementia agent. We explored in a series of models of increasing complexity, whether this voltage-dependent channel blocker had neuroprotective properties at clinically relevant concentrations. As expected, memantine protected neurons in organotypic hippocampal slices or dissociated cultures from direct NMDA-induced excitotoxicity. However, low concentrations of memantine were also effective in neuronal (cortical neurons and cerebellar granule cells) stress models dependent on endogenous glutamate stimulation and mitochondrial stress, i.e. exposure to hypoxia, the mitochondrial toxin 1-methyl-4-phenylpyridinium (MPP+) or a nitric oxide (NO) donor. Furthermore, memantine reduced lethality and brain damage in vivo in a model of neonatal hypoxia-ischemia (HI). Finally, we investigated functional rescue (neuronal capacity to migrate along radial glia) by memantine in cerebellar microexplant cultures exposed to the indirect excitotoxin 3-nitropropionic acid (3-NP). Potent NMDA-R antagonists, such as (+)MK-801, are known to block neuronal migration in microexplant cultures. Interestingly, memantine significantly restored the number of neurons able to migrate out of the stressed microexplants. These findings suggest that inhibition of the NMDA-R by memantine is sufficient to block excitotoxicity, while still allowing some degree of signalling.
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| 33. |
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